Two problems related to side/window air bag have been reported for the 2006 BMW X3. The most recently reported issues are listed below.
Had an accident on a city street. Vehicle was in motion & impact was on the front bumper. All airbags deployed except passenger side airbag. Vehicle had the passenger side airbag lamp illuminated for a while before the accident. Called dealer and BMW long back when I initially came to know about the recall. But I was told that my VIN is not in the recall list. Luckily there was no one in the passenger seat when the accident happened, else would have been worse. Nhtsa campaign number: 08v384000.
2006 BMW X3 passenger side airbag deactivation light come on intermittently. Sometimes the "fasten seat belt" light on the dash comes on while driving with a loud beep (while the driver is wearing the seat belt and there is no one or no object on the front passenger seat. This is more alarming as one is not sure if the air bag is going to work or not in emergency. This happens intermittently and searching the web shows others are having similar issues. I have taken it to the dealer a few times and each time they run some diagnostics, keep it overnight and tell me there is no faults registered, diagnostics found no issues, and they could not reproduce the problem and there is nothing they can do. Today they told me the same thing again and when I drove out of the dealership the fasten seat belt light went on with the beep but by the time I tured around to go back the alarm turned off. So I didn't go back. On the way home had to stop at the grocery and the light and alarm turned on again on the way home from grocery. It's pretty disappointing for a brand known for safety and quality.